Stoppings are used to control the flow of ventilation air through a mine. A stopping often includes an opening closed by a door to allow passage through the stopping, as described for example in our U.S. Pat. No. 7,393,025 incorporated herein by reference. Mine doors of this type, sold by Jack Kennedy Metal Products & Buildings, Inc., have proven to be commercially successful. These doors, sometimes referred to as “man doors”, are made from relatively thick sheet metal (e.g., 14 gauge metal) to provide the necessary strength. However, the additional bulk increases the expense of the door. There is a need, therefore, for a mine door which is lighter in weight and yet still very strong.
Also, some mine ventilation systems involve reversing air flow through the mine. That is, a mine passage that is an air intake at certain times later becomes an air return. Because it is advantageous for a mine door to be hung on its door frame such that the high pressure pushes the door closed against the frame to aid in both closing and sealing, it is also advantageous that the door be “reversible”, that it, the capability of being moved from one side of the door frame to the other at the time of air reversal. Further, it is desirable that the door be self-closing so that it cannot be left open inadvertently.
Heretofore, reversibility has been achieved in some cases by unfastening the hinges of the mine door from one side of the door frame and re-fastening the hinges to the opposite side of the door frame. This procedure is labor-intensive and time-consuming. In other cases, the door mounts on open topped hinge pins at one side of the door frame such that the door can be lifted off the hinge pins and moved to similar hinge pins on the opposite side of the door frame. However, the door is not self-closing. There is a need, therefore, for a self-closing mine door that can be quickly moved from one side of the door frame to the other.